65 lines
1.7 KiB
JavaScript
65 lines
1.7 KiB
JavaScript
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// BigInt keeps entered integers exact, even for very large countdowns.
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export function integer(value) {
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return /^\d+$/.test(String(value)) ? BigInt(value) : 0n;
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}
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export function splitSeconds(seconds) {
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return {
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minutes: String(seconds / 60n),
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seconds: String(seconds % 60n).padStart(2, '0'),
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};
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}
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export class Countdown {
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constructor(now = Date.now) {
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this.now = now;
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this.state = 'idle';
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this.finished = false;
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this.duration = 0n;
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this.remaining = 0n;
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this.deadline = 0n;
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}
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edit(minutes, seconds) {
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if (this.state === 'running') return;
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this.duration = (integer(minutes) * 60n + integer(seconds)) * 1000n;
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this.remaining = this.duration;
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this.state = 'idle';
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this.finished = false;
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}
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update() {
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if (this.state !== 'running') return;
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const delta = this.deadline - BigInt(this.now());
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this.remaining = delta > 0n ? delta : 0n;
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if (this.remaining === 0n) {
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this.state = 'idle';
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this.finished = true;
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}
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}
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toggle() {
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if (this.state === 'running') {
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this.update();
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if (!this.finished) this.state = 'paused';
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return;
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}
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if (this.finished) this.remaining = this.duration;
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this.finished = false;
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this.deadline = BigInt(this.now()) + this.remaining;
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this.state = 'running';
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this.update();
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}
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reset() {
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this.remaining = this.duration;
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this.state = 'idle';
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this.finished = false;
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}
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display() {
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// Round up so the timer only displays zero once its deadline is reached.
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return splitSeconds((this.remaining + 999n) / 1000n);
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}
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}
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